1. Field of the Invention
The present invention relates to an interface and a communication device.
2. Description of the Related Art
Communication terminals, representative examples of which are cellular phones, have recently had functions equivalent to those of personal computers as a result of advances in processors. In particular, a communication terminal that is provided with a graphical user interface (GUI) can provide a user with an interface for applications. Therefore, such a communication terminal is expected to be used in near field communication conforming to the near field communication (NFC) standard other than being used as a telephone.
In the related art, in order to perform near field communication, an antenna that is disposed on a rear surface side of a communication terminal needs to be brought close to an external device with which the communication terminal communicates. Thus, a mark that indicates the position of the antenna is provided on the rear surface of the communication terminal.
However, in the case where a cover or the like that is made of a silicone rubber is mounted on the communication terminal, the mark, which indicates the position of the antenna, cannot be visually recognized from the outside. In addition, in the case where a housing of the communication terminal is made from a metal such as aluminum or stainless steel, there are disadvantages in that an area in which the communication terminal can perform communication may sometimes be small and there is a possibility that the communication terminal cannot perform communication. In the case of trying to read information that is recorded on an IC card by using a relatively large communication terminal such as a tablet terminal, it would be convenient if near field communication can be performed on a front surface side of the communication terminal.
Accordingly, a technology for realizing near field communication performed on a front surface side of a communication terminal has been proposed (see, for example, Japanese Unexamined Patent Application Publication No. 2006-195802). A reader-writer disclosed in Japanese Unexamined Patent Application Publication No. 2006-195802 includes an antenna that is superposed with a display screen of a liquid crystal panel. Thus, the reader-writer can communicate with a device or an IC card located on a front surface side of the liquid crystal panel with good efficiency.
The antenna of the reader-writer disclosed in Japanese Unexamined Patent Application Publication No. 2006-195802 is formed by depositing a transparent conductive material on a transparent substrate, which is superposed with the liquid crystal panel, by sputtering and by performing patterning of the transparent conductive material. Thus, the degree of freedom when designing the antenna is smaller than that when designing a versatile antenna. In the case where an antenna is formed by the above method, an antenna coil is formed when a display is manufactured. Consequently, in the case where a design change is made in a housing in which the display is to be accommodated after the display has been manufactured, and where the antenna characteristics deteriorate, it becomes difficult to address the deterioration.
Indium tin oxide (ITO) is often used as the transparent conductive material. However, the conductivity of ITO is one hundredth or less than the conductivity of copper, aluminum, silver, or the like. Thus, it is difficult to obtain a sufficient Q value by using an antenna that includes a coil made of ITO, and there is a problem in that communication quality becomes inconsistent.